1. Field of the Invention
The present invention pertains to a stabilized biocidal composition, a paint containing the stabilized biocidal composition, and a method for protecting a substrate from fungal infestation with the stabilized biocidal composition. The stabilized biocidal composition comprises a halopropynyl compound and a UV absorber selected from the group consisting of the esters of 4-alkoxy benzylidene malonic acid, the esters of 2-cyano-3,3-diphenyl acrylate, 3-(4-methylbenzylidene)camhor, 4-alkoxy-2-hydroxybenzophenone, and 2-2-hydroxy-3-t-butyl-5-(2-octyloxycarbonyl)ethylphenyl!2H-benzotriazole.
2. Description of the Background
Both exterior and interior surfaces, substrates of all types and organic compositions and formulations, when exposed to common environmental conditions, e.g. moisture, are prone to attack, discoloration and various kinds of destruction by a variety of species of microorganisms, including fungi, algae, bacteria and protozoa. As a result, there has always been a great need for effective and economical means to protect, for extended periods of time, commercial compositions and formulations from the deterioration and destruction caused by such microorganisms.
The type of materials which need protection against such microorganisms include, for example, materials such as paints and other coating formulations, surfactants, proteins, starch-based compositions, inks, emulsions and resins, stucco, concrete, stone, and cementaceous surfaces, wood, caulking, sealants, leather, plastics, and textiles. Other important commercial materials such as polymer dispersions or aqueous latex paints containing polyvinyl alcohol, polyacrylates or vinylpolymers, thickener solutions containing cellulose derivatives, kaolin suspensions and metal working fluids, also are prone to degradation by the action of objectionable microorganisms which can significantly impair the usefulness of such compositions. Such degradation may produce, inter alia, changes in pH values, gas formation, discoloration, the formation of objectionable odors, and/or changes in rheological properties.
Wooden objects, for example, are subject to degradation from a wide variety of natural pests. Fungi are particularly prevalent and include brown rots, white rots and soft rots. Fortunately, a variety of compositions have been developed for treating wooden objects and other materials and surfaces to retard the destructive effect of such pests.
A great deal of effort has gone into developing a wide variety of materials which, to various degrees, are effective in retarding or preventing the growth of, and accompanying destruction caused by, such microbes in a variety of circumstances. Such biocidal compounds include halogenated compounds, organometallic compounds, quaternary ammonium compounds, phenolics, metallic salts, heterocyclic amines, formaldehyde donors, organosulfur compounds and the like.
One of the most effective and best known classes of biocides used in such compositions are those containing a halopropynyl moiety, and especially an iodopropynyl moiety. Such compounds are widely disclosed in the patent literature including U.S. Pat. Nos. 3,660,499; 3,923,870; 4,259,350; 4,592,773; 4,616,004 and 4,639,460 to name a few. Included within this class of compounds are the halopropynyl carbamates which are known primarily for their fungicidal activity. Among these is 3-iodo-2-propynyl butyl carbamate, also referred to as IPBC, which is one of the best known and probably the most widely used of the halopropynyl carbamate fungicides. It is a highly active broad spectrum fungicide and, in addition to its fungicidal activity, it has also been associated with algaecidal activity as disclosed in Great Britain Patent 2,138,292 and U.S. Pat. Nos. 4,915,909 and 5,082,722.
Despite their wide acceptance, the halopropynyl carbamate biocides have been reported to be prone to degradation under certain conditions, sometimes resulting in some discoloration and yellowing. In those instances where degradation does occur, and especially in those instances where this degradation results in discoloration and yellowing, the use of such halopropynyl carbamate biocides has been limited, especially in compositions where a white or clear color is desired such as in white caulks, white paints, paper coatings, plastics, plastic coatings and the like.
It has also been suggested that such products may be incompatible with the driers used in certain solvent based systems and that such driers and other potential additives may cause a slow degradation of the biocide.
Each application or system can present its own set of unique conditions and circumstances that may affect the performance of a particular substance and which in turn may require its own unique or specific remedy to insure that acceptable performance is maintained. There is, therefore, a constant need to find improved additives and conditions that will sufficiently inhibit the loss of activity whenever it is necessary to use the antimicrobial under conditions that may pose a threat to its integrity.
A number of attempts to mitigate such problems for a variety of applications have been reported. For example, see Gabriele et al., (U.S. Pat. No. 4,552,885, Journal of Coatings Technology, 56(712):33-48), Singer (U.S. Pat. No. 4,276,211) and Long (U.S. Pat. No. 4,297,258). While many of these have found some success in certain applications, none provides a sufficient remedy for all cases. Degradation remains a problem in many instances, therefore, and there is a constant need for new and better remedies.
The present invention provides a significantly more effective way to stabilize halopropynyl compounds, and particularly a halopropynyl carbamate fungicide such as IPBC (known in commerce as Troysan Polyphase.RTM.), against the undesirable degradation and yellowing caused by exposure to UV radiation.